Parsons shaw



(ModeL) P. smurv.

DENTAL ENGINE.

Patented Nov EEEEEE ATTORNEYS.

WITNESSES N. PETERS. P1 mo-Llflmgnpher, Wishingion. n. c.

IlNrrsD STATES PATENT OF ICE. 1

PARSONS SHAW, OF MANCHESTER, COUNTY OF LANCASTER, ENGLAND.

DENTAL ENGINE.

SPECIFICATION forming part of Letters Patent No. 249,111, dated November 1, 1881.

Application filed June 7,1881. (ModeL) Patented in England January 3, 188].

To all whom it may concern:

Be it known that I, PARSONS SHAW, of Manchester, in the county of Lancaster, England, have invented certain new and useful Improvements in Dental Engines, (for which I have obtained a Patent in Great Britain,No. 20, hearing date January 3, 1881;) and I hereby declare the following to be. a full, clear, and exact descriptionthereof, reference being had to the annexed drawings, forming part of this specification.

The main object of the invention is to im prove the universal joint employed in dental engines by a hinge movement which will allow the swinging arm to play freely in any direction without straining the spiral transmitter or causing it to bind or buckle. This I accomplish by using bifurcations on the bearings and bending their ends at right angles to the bearings, then connecting these ends by pivots, all as hereinafter described.

The mechanism employed by me in performing my invention is illustrated in the accompanying drawings.

Figure l is an elevation of the entire machine. Fig. 2 is a side view of my improved universaljoint. Fig. 3 is another view of the same. Fig.4is a plan ofthe same when straightened; and Fig. 5 shows myimproved chuck.

Similar letters refer to similar parts in the different views.

I make use of a vertical tubular standard, a, the base of which I fit on a tripod or other stand, I), to which the treadle c is connected. I mount the driving-wheel d on the side of the standard, and near the floor, by preference, to insure steadiness. On the upper part of the standard a I mount a horizontally-swinging crane, which consists of a rod,f, a driven shaft, 9, a stay, j, a bearing, 6, mounted on the top of the rod f, and two bearings,i and 1, at the end of the stayj. The rodfslides in a telescopetube in the standard a, and the rod and the movable bearing 1 at the bottom of the stayj allow the crane to freely rotate. One end of the shaft 9 revolves in the bearing 6, and outside the bearing the shaft is attached to the pulley h, which has two or more grooves of different sizes. The pulleys receix e motion bya band from the driving-wheel d. The other end of the shaft 9 is attached to a spiral transmitter, 8, carried by my improved double-forked universal joint, to be described. By this spiral transmitter motion is imparted to a loose swinging arm or second shaft, 7;. This shaft imparts motion, through another spiral transmitter inclosed in the sheath n, to a shaft in the hand-piece 0, on which the instrument to be used is fastened, as hereinafter described.

I make use of a collar with a set-screw, 2, on the rodf, and a collar with a set-screw, 3, on

the standard to below the bearing lon the stay j, which serve the purpose of raising and lowering the swinging crane and adjusting it in proper position.

Fig. 2 is a side view of my improved universaljoint when the engine is at rest and the arm k is at right angles to the arm g. Fig. 3 is a side view of the same when bent double and the two shaftsg and k are parallel to each other. Fig.4 is a plan of the same when seen from the top and when straightened so that the shafts g and 7c and the transmitter s are in a continuous line.

My universal joint consists of a double-sleeve fork-joint and couplings. In each part or joint of the couplings there is a cylinder or sleeve on and 1', which form bearings to the shafts g and k. From the cylindrical part of the couplings extend two forks, 4 and 5, which end in right-angle projections. These projections are connected together at the ends t by means of pins, which form a hinge and allow them to move freely on one another. Between these forks runs the transmitter s, which is fastened to the shaftsg and It by meansofnuts, into which the shafts are screwed. These nuts form col lars to keep the shafts in the bearings m and r, and the one attached to the shaft 9 holds the first part of the universaljoiut in its bearing 1..

The transmitter 8 is protected from injury and prevented from buckling by means of a spiral sheath, 1, fitted at each end on cylindrical projections from the sleeves m and 1', and is itself protected by the sides of the forks 4 and 5, between which it is placed. On the forks 4 and 5 are arranged stops 6 to prevent the couplings from-bending except on the sides fromiwhich theZright-angle projection otzthe forks arise. By preference, the stop prevents thejoint from becoming quite straight, so as to prevent it turning round with the transmitter.

The change in the length of the transmitter s, as it is straight or curved, is compensated by allowing the shaft 9 a little play on the bearing 0 and a little play to the shaft k in its bearing on the sleeve 0'. The cylindrical or sleeve part m of the first joint always remains in a line with the shaft g, and rotates freely in the bearing i attached to the stay j, and this gives one of the motions of the universal joint. The other is got by the transmitter s, which runs freely either straight or bent, protected by the spiral shaft land the novel right-angle termination of the forks 4 and 5, connected by the hinge f, by which the transmitter, however much or little it is bent, is always maintained in a simple curve.

Fig. 5 shows a hand-piece in section, in which runs a short shaft at the end of which is the chuck p, which is slightly tapered inside, and when the end of the implement, which is tapered to correspond, is pressed in it is held firmly. I thus dispense with the use of springs or screws and other devices for holding the implement.

I am aware that the shaft and its connected arm or section have been connected with the opposite ends of a wire coil, and that the forks or yokes have been jointed, but not bent at the ends.

What I claim as new and of my invention 1. In a dental engine, the con1bination,with the drive-shaft g, transmitter s, and swinging arm k, said shaft and arm being attached to opposite ends of the transmitter, of the forked sleeves m 0', having their prongs end-bent at about a right angle and connected by a pivot, as shown and described, whereby the arm k may be allowed free play without straining the transmitter or causing it to buckle.

2. In a dental engine, the stayj, provided with an adjustable collar at each end, in combination with the rods at], the drive-shaft g, and the bearings c i, as and for the purpose specified.

PARSONS SHAW.

Witnesses:

HENRY BERNOULLI BARLOW, CHARLES ALFRED BARLOW. 

